First time poster. My accord had a CEL come on a while back. P0401 & p0420, pulled the intake and cleared the egr valve. water pump began leaking, had that changed. Two days later, CEL back on, this time P0170 & p0171. Ran some seafoam through, ready to get in and redo tubes and gaskets. Had the code cleared. Stayed off, until 92 miles later. Completely new code: P1456. I've had an occasional gas scent, never anything longer than a few seconds after turning off the engine. The whole time all this is occurring, at seemingly random times, my car feels like it is out of gas: speed drops, rpms drop, push the gas and jumps back to normal. At cold start, about 40mph, and about 60 mph is when it seems to happen most. Not all the time, and not any consistent pattern. I am at a loss to try to figure out what is causing all this at once. Am I so lucky that I had all these separate ailments happen within 2 months? Oh yes, inspection exp. 7/31, so ideally I'd like to figure out soon. Any thoughts, before I begin replacing everything?


99 accord ex v6

 

1. What trouble code(s) are currently still existing (P1456 and others)?

2. Have you tried resetting the PCM/ECM to see what comes back?

 

The most recent code was p1456, which I reset this morning (pulled the fuse) after checking the cap and connections, and driven about 20 miles. No code is on yet. Still shudders like it is out of gas. Like I mentioned, it isn't an ongoing thing. But when it does it, it will do that for a while.

 

Check your fuel trims and see if running lean. You had P0170,171 a one point.
If lean try to determine if air or fuel. If stft drops at higher RPMs suspect vacuum leak, if not then suspect lack of fuel.
If your scanner reads live data use that to troubleshoot. Resist the urge to replace parts hoping for a fix. There's a probability to cause additional problems while changing parts.

 

P1456 is a leak in the EVAP system. Basically, your fuel tank isn't airtight like it should be.

Obviously, check gas cap's seal.

Then look for rotted or disconnected hoses around the EVAP canister (underneath the car below left-rear seat). Most of those would throw P1457 but still worth checking. There's a fuel-tank pressure transducer down there somewhere that can have a problem.

The shop manual has quite a few pages full of checks for P1456 & P1457.